A time measurement circuit of this type is shown in FIG. 12 by way of example. An example of a general-purpose time measurement circuit is shown in FIG. 9. FIG. 12 is a block diagram of a prior-art semiconductor integrated circuit comprising a time measurement circuit that operates on an auxiliary clock signal.
The semiconductor integrated circuit comprises a main circuit 710 drive on the basis of a main system clock signal 760, an auxiliary circuit 730 driven on the basis of an auxiliary clock signal 770 with the objective of providing timing or the like, and an interface circuit 720 that electrically connects together the auxiliary circuit 730 and the main circuit 710 by inter-block signals 781, 782, and 783. In this case, the main system clock signal is a clock for driving the main circuit and the auxiliary clock signal is an assistant clock for providing timing for measuring the passage of time, by way of example,
In addition, the semiconductor integrated circuit comprises a main power supply circuit 750, which is connected electrically to the main circuit 710 and supplies a potential to the main circuit 710, and an auxiliary power supply circuit 740, which is connected electrically to the auxiliary circuit 730 and supplies a potential to the auxiliary circuit 730.
Within the main circuit 710 are a first control circuit 712, which receives the main system clock signal 760 and operates in accordance with this main system clock signal 760, and a second control circuit 714, which is connected electrically to the first control circuit 712 by an inter-block signal 762 and is connected electrically to the main power supply circuit 750 by the inter-block signal 764.
Within the auxiliary circuit 730 are a first control circuit 732, which receives the auxiliary clock signal 770 and operates in accordance with this auxiliary clock signal 770, a second control circuit 734 connected electrically to the first control circuit 732 by an inter-block signal 772, and other circuits 736.
In the semiconductor integrated circuit of the above described configuration, the main system clock signal 760 of the main circuit 710 can be halted by the inter-block signal 764, independent of the auxiliary circuit 730.
However, this auxiliary circuit 730 is unable to continue operating independently of the main circuit 710, nor can the auxiliary clock signal 770 be halted. This leads to a problem in that, although the power consumption of the main circuit can be constrained if necessary, it is not possible to halt the auxiliary circuit and the auxiliary power supply and thus the auxiliary circuit always consumes power, which makes it impossible to reduce the power consumption of the entire semiconductor integrated circuit.
Since the auxiliary clock signal 770 cannot be halted, circuits driven by this clock signal 770 continue to operate regardless of whether or not they are necessary, which increases the power consumption. In particular, if the auxiliary circuit 730 is configured as a time measurement circuit, by way of example, a problem occurs in that a fixed period of time is measured thereby and the auxiliary circuit 730 cannot be halted, even when there is no need to measure time beyond that fixed period, so it is not possible to constrain the power consumption during the time after that fixed period, when there is no longer any need to continue the measurement.
In addition, semiconductor devices with lower voltage specifications are becoming more popular from the viewpoint of reducing the power consumption, and the operation of a time measurement circuit has a large effect on power consumption, even in a semiconductor device which is used together with a time measurement circuit mounted thereon, and thus there are demands for further reductions in power consumption.
The present invention was devised in the light of the above described technical concerns and has the objective of providing a semiconductor integrated circuit, a semiconductor device, and electronic equipment that comprises the same, which are capable of halting the auxiliary circuit when it is not required, to constrain the amount of power consumed by that auxiliary circuit, thus enabling a reduction in the power consumption of the entire semiconductor integrated circuit.